Apparatus for treating slag



NOV. 8, 1966 G BARTHOLOMEW 3,284,166

APPARATUS FOR TREATING SLAG Original Filed June 6, 1963 38% WET. i 8 25' I Oxygen 54 Oxygen 52 46 Q 42 Fue 44 //V VE'I'V TOR GEORGE A BA RTHOLOMEW Attorney United States Patent M 2 Claims. (Cl. 23259.1)

This application, which is a division of my co-pending application,Serial No. 286,084, filed June 6, 1963, relates to apparatus fortreating slag and more particularly to treating metallurgical slags suchas blast furnace and open hearth slags while they are in a moltencondition. Slag compositions have long been modified by adding materialsthereto, especially in the manufacture of slag cements. This has beendone in various ways such as by mechanical mixing or by passing amixture of slag and additives through a rotary kiln in which they areheated to incipient fusion. Mechanical mixing has the disadvantage thatthe reaction of the constituents is slow and incomplete. Kiln burnedslag products have more uniformity than raw mixtures, but the process isexpensive because of the cost and inefficiency of the equipmentrequired.

The operation of blast furnaces has also been modified to obtain a slaghaving the desired characteristics for cement use. This involvesmodifying the charge into the furnace and also varying the operation ofthe furnace in other respects. This has the disadvantage that it may notbe possible to operate the furnace in the most efficient way to producepig iron. Another disadvantage is that some slag alloying constituentscannot be charged into the furnace because of their effect on furnacelinings or the like.

Additives have also been made to slag to make it more suitable for soiltreatment. This may be done by mechanical mixing or by adding materialto molten slag. The disadvantages of mechanical mixing are pointed outabove. When material is added to molten slag the slag must be maintainedmolten for sufficient time to permit the desired reactions to occur,especially when the product to be obtained has a higher melting pointthan the slag.

It is therefore an object of my invention to provide apparatus fortreating molten metallurgical slag by which heat and mineral componentsare added thereto in such a manner that the desired compositions can beobtained.

Another object is to provide such apparatus which may be used to obtaina product having a melting point higher than that of the slag.

These and other objects will be more apparent after referring to thefollowing specification and attached drawings, in which:

FIGURE 1 is a schematic view, partly in section, showing apparatus usedin the practice of my invention; and

FIGURE 2 is an enlarged view, partly in section, of the lance shown inFIGURE 1.

Referring more particularly to the drawings, reference numeral 2indicates a granulating pit having water W therein. A track 4 isprovided adjacent the pit 2 for supporting a ladle car 6 having a ladle8 mounted thereon for receiving molten metallurgical slag S. A hood 10may be supported above the ladle 8 for receiving fumes and dust. Thehood 10 is connected by means of a conduit 12 to a precipitator 14. Oneleg of a U-shaped lance 16 passes downwardly through the hood 10. Thelance 16 includes a cooling chamber 18 through which water is circulatedfrom an inlet 20 to an outlet 22. The lance 16 also includes fuelconduit 24 and an oxygen 3,284,166 Patented Nov. 8, 1966 and additiveconduit 26. The conduit 24 extends upwardly to a horizontal portion 28to which is attached a downwardly extending leg 30. The conduit 26 has ahorizontal portion 32 and a downwardly extending leg 34 surrounding theleg 30. The conduits 24 and 26 are arranged coaxially. An eye 36 isattached to the horizontal portion 32 for receiving a wire rope 38 whichmay be attached to a crane or other lifting device, not shown.

A double conduit 39 is slidably received Within the leg 34. The conduit39 has an outer chamber or conduit 40 which is connected to the conduit26 and an inner chamber or conduit 42 which is connected to the conduit24. Conduit 40 is connected to a T 44. A conduit 46 is attached to theside outlet of the T 44 and leads to two oxygen containers 48 and 50which contain oxygen under pressure. It will be understood that the gasin containers 48 and 50 may be commercially pure oxygen, air or amixture of air and commercially pure oxygen. It will be in this sensethat the term oxygen will be used hereinafter and in the claims. Valve52 controls the flow of oxygen from tank 48 and a valve 54 the flow fromtank 50. Outlets 56 and 58 from conduit 40 lead to pressurized storagetanks 60 and 62, respectively. These tanks contain mineral components ofthe desired type. A conduit 64 leads from tank 48 to tanks 60 and 62,valves 66 and 68 being provided therein to control the flow of oxygen. Asimilar conduit 70 leads from tank 50 to tanks 60 and 62 with valves 72and 74 being provided to control the flow of oxygen to these tanks.Metering valves 76 and 78 are provided in the conduits 56 and 58,respectively, to control the flow of material from the tanks 60 and 62.Conduit 42 extends through T 44 to a fuel tank 80, a valve 82 beingprovided to control the flow of fuel.

In operation, the tanks 60 and 62 are filled with the desired mineralconstituents. The mineral constituents are in granular form and shouldbe of such size that all particles will pass through a No. 4 mesh sieve.Preferably the particles should be more finely grated so that thereofwill pass a 20 mesh sieve and 35% pass a mesh sieve. A ladle 8 ispositioned beneath the hood 10 and the lance 16 is lowered so that itsend is below the level of the molten slag S and the valves 52, 54, 66,68, 72, 74, 76, 78 and 82 adjusted to provide the desired amount offuel, oxygen and additives. The fuel and oxygen are kept separate untilthey exit from the bottom of the lance 16. The fuel and oxygen willcombine and burn within the molten mass with the heat increasing thetemperature and fluidity of the slag, thus facilitating the escape ofgaseous materials and efficiently degasing the slag. Since the lancenozzle is submerged in the molten mass the heat is transferred rapidlyand efiiciently to the slag and there will be thorough mechanical andthermal mixing of the mass. Since the mineral additives are introducedand dispersed into the hottest portion of the mass the reaction betweenthe components will be rapid and thorough. After the desired additionshave been made the lance 16 is raised and the molten slag dumped intothe Water W so as to quench it rapidly to an amorphous glassy state. Insome cases it will be advantageous to cool the slag slowly to acrystallized state. To do this the water is removed from the pit 2before dumping the slag. The velocity of the fuel, the oxygen and theadditives may be varied. When adding small amounts of low melting pointadditives and using tar as the fuel, the gas velocity may be as low as20 ft. per second. When adding large amounts of higher melting pointadditives and using a gaseous fuel the gas velocity may be as high as1500 ft. per second. In most cases, however, the velocity would bebetween 100 and 500 ft. per second.

When preparing a soil treatment composition the operation is as follows.Assuming that there is 12.22 tons of open hearth slag in moltencondition in the ladle 8, granulated rock phosphate in the tank 62,granulated potash in the tank 60, natural gas in the tank 80 and airunder pressure in the tanks 48 and 50, 20 tons of the soil treatmentcomposition can be obtained as follows: The valve 78 is set to remainopen until 6.11 tons of rock phosphate is fed into the ladle 8 and thevalve 76 set to remain open until 1.67 tons of potash is delivered tothe ladle 8. Natural gas and air will be delivered to the lance 16 asdescribed above to supply sufiicient heat to keep the mixture in theladle 8 molten. Since the composition has a lower melting point than theslag, part of the heat necessary to keep the mixture molten will beprovided by the slag while the remaining heat will be supplied byburning of the natural gas. When the desired amount of phosphate andpotash has been fed natural gas will continue being burned for a periodof time sufficient to complete the reactions. The lance 16 is thenremoved and the slag dumped into the water W. This provides acomposition having approximately 10% available phosphate and availablepotash.

When preparing Portland cement the operation is as follows. Assumingthat there is tons of molten blast furnace slag in the ladle 8, granularlime in the tank 62, oxygen in the tanks 48 and 50 and fuel oil in thetank 80, approximately fifteen tons of Portland cement can be obtainedas follows: The valve 78 is set to remain open until 5 tons of lime(CaO) is delivered to the ladle 8. Fuel oil and oxygen will be deliveredto the lance 16 as described above to supply sufficient heat to keep themixture in the ladle 8 molten. Since the composition has a highermelting point than the slag more heat must be supplied than when makingthe soil treatment composition described above. When the desired amountof lime has been fed, heat will continue to be supplied by the burningof the fuel for a period of time suflicient to complete the reactions.The lance 16 is then removed and the slag dumped into the trough 2 whichmay or may not have water therein. Assuming a blast furnace slagconsisting of CaO, 32% SiO 10% A1 0 6% MgO and 2% Fe O the modified slagwill consist of 64.2% CaO, 21.6% SiO 6.8% A1 0 4% MgO and 1.4% Fe O Themodified slag is then ground to size to provide Portland cement of ananalysis within limits specified.

While several embodiments of my invention have been shown and described,it will be apparent that other adaptations and modifications may be madewithout departing from the scope of the following claims.

I claim:

1. Apparatus for treating molten metallurgical slag comprising acontainer for receiving molten slag, a vertically movable U-shaped lancehaving an inner conduit surrounded by an outer conduit, one leg of saidlance being movable from a position where its lower end is below saidslag to a position where its lower end is above said slag, an additivecontainer, an oxygen container, a source of fuel, a double conduithaving an inner chamber surrounded by an outer chamber, means connectingsaid source of fuel to said inner chamber, and means connecting saidadditive container and said oxygen container to said outer chamber, saiddouble conduit being received within the second leg of said lance withits inner chamber connected to said inner conduit and its outer chamberconnected to said outer conduit.

2. Apparatus according to claim 1 including means for controlling theflow of fuel, oxygen and additive to said double conduit.

References Cited by the Examiner UNITED STATES PATENTS 1,932,656 lO/1933Fleming et al. 24

JOHN F. CAMPBELL, Primary Examiner.

M. L. FAIGUS, Assistant Examiner.

1. APPARATUS FOR TREATING MOLTEN METALLURGICAL SLAG COMPRISNG ACONTAINER FOR RECEIVING MOLTEN SLAG, A VERTICALLY MOVABLE U-SHAPED LANGEHAVING AN INNER CONDUIT SURROUNDED BY AN OUTER CONDUIT, ONE LEG OF SAIDLANCE BEING MOVABLE FROM A POSITION WHERE ITS LOWER END IS BELOW SAIDSLAG TO A POSITION WHERE ITS LOWER END IS ABOVE SAID SLAG, AN ADDITIVECONTAINER, AN OXYGEN CONTAINER, A SOURCE OF FUEL, A DOUBLE CONDUITHAVING AN INNER CHAMBER SURROUNDED BY AN OUTER CHAMBER, MEANS CONNECTINGSAID SOURCE OF FUEL TO SAID INNER CHAMBER, AND MEANS CONNECTING SAIDADDITIVE CONTAINER AND SAID OXYGEN CONTAINER TO SAID OUTER CHAMBER, SAIDDOUBLE CONDUIT BEING RECEIVED WITHIN THE SECOND LEG OF SAID LANCE WITHITS INNER CHAMBER CONNECTED TO SAID INNER CONDUIT AND ITS OUTER CHAMBERCONNECTED TO SAID OUTER CONDUIT.